Assessment of dicing induced damage and residual stress on the mechanical and electrical behavior of chips

Due to increased technological and economic requirements during wafer production several materials like metal structures or brittle low-k materials are placed within the dicing street. These materials have a negative effect on the quality and reliability results when using conventional separation methods like mechanical dicing. For this case a laser grooving step, prior mechanical dicing is used to remove these materials out of the dicing street. It is known that each of this separation method creates residual stress in the adjacent material in terms of specific strain fields. In the present study the influence of the strain fields on the mechanical and electrical behavior of chips was investigated. For this reason several laser grooving processes and a mechanical dicing process was compared using a dedicated dicing test chip with sensors to measure the electrical behavior. The mechanical fracture strength of the chips was investigated by 3-point bending tests. Photoelastic stress measurements were used to characterize resulting strain fields. The more extensive the strain fields, the lower the fracture strength, the greater the number of electrically conspicuous chips. The combination of strain field, electrical and mechanical strength characterization can help to optimize the process parameters get better reliability and quality of chips.